Okla. Stat. tit. 21, § 21-491: Perjury defined - Defense

Whoever, in a trial, hearing, investigation, deposition,

certification or declaration, in which the making or subscribing of

a statement is required or authorized by law, makes or subscribes a

statement under oath, affirmation or other legally binding assertion

that the statement is true, when in fact the witness or declarant

does not believe that the statement is true or knows that it is not

true or intends thereby to avoid or obstruct the ascertainment of

the truth, is guilty of perjury, a Class D1 felony offense. It

shall be a defense to the charge of perjury as defined in this

section that the statement is true.